The Helmholtz Resonance

By Ross Engel

It should be no surprise to you, our intrepid readers, that the authors here at Jagged Word do occasionally enjoy beverages that come out of bottles. Water, Wine, Whiskey, Beer. If it can be bottled, we tend to like it. And it is safe to say that we all have our favorites—our go to beverages of choice.

The other night, after mowing the lawn and grilling dinner, I more than earned a delicious and refreshing beverage. And after finishing that particularly rewarding and refreshing beverage, I amazed my children by making music sound forth from my empty bottle. My son James watched in wonder and amazement. My daughters giggled as I interrupt our quiet dinner with the deep sound that only an empty bottle can make. Their pleas to “do it again” were met with gusto, and I even took the time to open a fresh bottle to demonstrate the way the pitches change depending on how full or how empty the bottle is. They were thoroughly impressed. They joyfully confessed that their father can do anything.

Of course, as adults, this pub trick isn’t all that exciting. In fact, it might even be deemed annoying. It might even make one’s wife’s eyes roll, especially as the loud sound continues to bellow through her dinner. So, you need to impress the other adults with some science, and the scientific term for the sound made from blowing across a bottle is the “Helmholtz resonance.” Now when someone gets annoyed at your bottle blowing noises, you can just tell them to stop hating on your Helmholtz resonance.


The reason I’m sharing this story with you isn’t for the purpose of helping you annoy your dinner guests or even to amuse your children, though that may be an added perk. The truth of the matter is, sometimes I feel like an empty bottle. Sometimes I feel like I’ve got nothing left to give. Perhaps you’ve felt that way before too!

I look at the calendar each week and know full well that another Sunday is coming, and that means another sermon to write and deliver. Another blog deadline is approaching, which means another post to write. A new month on the horizon means another newsletter article to write. For me, it often seems like a great deal of time is spent writing, drafting, and trying to put the right words together to get a message across. And sometimes putting the words together means digging deep, scraping the bottom of the barrel, and hoping to come up with something. And sometimes it’s easy to feel as though you’re coming up empty.

For the non-clergy, maybe it’s not a sermon deadline or a blog deadline. Maybe it’s that feeling of not knowing what to say when a friend or family member comes to you for words of help or comfort, and when they look to you to speak something of Jesus to them in their time of need. It’s that feeling of not knowing what to say when you’ve been put into a position where you are being asked to speak on behalf of Jesus to someone’s hurts, worries, fears, struggles, and questions, and you just don’t know what to say because you feel empty yourself.

Deep down, we have all experienced the fear that comes from being called upon to speak for Jesus, from the pastor in the pulpit to the child in the pew and everyone in between. And the fear comes because we know what empty vessels we all truly are. We know our sin. We know our temptations. We know the things that trip us up each day. We know, more than we ever dare to admit, just how sinful and empty we are. And our sinful emptiness often stares us right in the face, doesn’t it? It’s the face we see when we look in the mirror. It’s the face that makes us ask the question, “How could God ever use someone like me? I’m just. So. Empty?”


What do I say? I’m struggling with this issue myself. How the heck am I supposed to help them, too? And we wonder and we question and we doubt. How do you share the joy of the Gospel when you feel crushed by the weight of the Law and your own damnable sin? How do you speak for Jesus when you yourself need someone to speak Jesus to you? And those thoughts start to make you realize how empty you are, and we start to think that we’re all alone.

But we’re not alone. God has not left any of us alone. In Baptism, God has joined us together to be a people. He has united us all in Christ. He has surrounded us with a cloud of witnesses. He gives us people who speak of Jesus and who speak of Jesus for you. And so when you can’t speak of Jesus or struggle to find the words to comfort another, turn to those people— a verse from a hymn, a Bible passage memorized years ago, a quote from another faithful Christian (perhaps a Luther quote), or something you vaguely remember from confirmation class, and let that speak.

The truth of the matter is that when we’re given the opportunity to proclaim Jesus, to stand up in whatever situations God has placed us into to speak for Him, it’s not about us. It’s not about you. It’s not about me. It’s not about the bottle. It’s not about how full or how empty we think we are. It’s all about the One who whose very breath gives life and voice and who makes all creation sing.

This past Sunday, my congregation celebrated the Festival of the Holy Trinity. We read in Acts 2:14a, “Peter, taking his stand with the eleven, raised his voice and declared to them.” Peter stood up among the other eleven disciples on Pentecost and preached. Peter, of all people, preached! He was the one who denied His Lord three times. He was the one who, with his own lips, emptied himself completely of Jesus saying, “I swear that I do not know the man.” This same Peter got up on Pentecost and preached to the crowds of people. And that crowd heard, they repented, and they were baptized. And some three-thousand people were added to the fellowship of the disciples that day.

In the midst of it all, it is good for us to be reminded that it wasn’t because of Peter that all this happened. It wasn’t because of how eloquent Peter was. It had nothing to do with whether he was an empty or full bottle at the time. It never actually is about the deliverer; it’s never about the bottle. It’s always only about the One who breathes. It’s about the One who can work through the emptiest, dingiest, unassuming individual—the emptiest bottle on the pile—and sound forth the song of Salvation with His breath.

It’s about Jesus. It’s always about Jesus. Jesus, the One who breathes and makes things happen. It’s not about you or me. We’re just the bottle. And it’s not about what kind of bottle we are, whether empty or full, it’s about the One whose very breathe gives life to empty bottles and who makes beautiful sounds flow forth from even the most unexpected places.